1. Field of the Invention
The present invention relates to the structure of a yo-yo.
2. Description of the Related Art
Yo-yos that are very familiar to everyone as toys are disclosed in, for example, U.S. Pat. No. 4,895,547 or Japanese Patent Publication (examined) No. 57-12633.
The yo-yo disclosed in U.S. Pat. No. 4,895,547 includes two yo-yo halves or rotary elements spaced a predetermined distance from each other, an axle for connecting the two yo-yo halves, and a spool mounted for free rotation on the axle. Threaded ends of the axle are screwed into threaded inserts embedded in the two yo-yo halves, respectively.
In this yo-yo, however, there is a possibility that the threaded ends of the axle may be loosened or removed from the inserts when a rapid reverse spin of the yo-yo halves occurs during operation.
The yo-yo disclosed in Japanese Patent Publication No. 57-12633 includes two yo-yo halves spaced from each other and each having a center hole defined therein. This yo-yo has a sleeve structure in which opposite ends of an axle are securely received in sleeves fitted inside the center holes of the two yo-yo halves, respectively.
Although the sleeve structure achieves complete fixing of the two yo-yo halves, maintenance work such as, for example, replacement of parts are not possible.